Hey Jakob
Yes indeed "Follow track Stacks" is checked.
Yes - it was a stack of only auxes and leaving the instrument track outside.
I can actually make a stack from those aux tracks including the instrument track- and that folds up ok, both in main and mix window. I more wanted to be able to group up certain parts of the kit together within perhaps a final "drums" stack. And this seems possible normally but just not when the input for the auxes is the instrument track itself. (hope thats clear)
For instance if I just create a load of aux tracks that have mic/line or bus inputs... I can make a stack from those (which folds up in the mix window) and then I can make a further stack out of that aux stack and the instrument track and they all fold up correctly. But the stacks I try to make with the auxes that have the instrument as input behave differently. (Apologies - I'm finding int a little hard to explain)
If I was happy enough to do the writing part / record down the audio to those aux tracks and then deleted the instrument track / reset all inputs to auxes - I'm sure that I could make kick sum stack / snare sum stack etc etc - then include all those in an all drum stack. I just hoped I could do that as I go